The present invention relates to a living body inspection apparatus for inspecting swallowing by a living body (an operation of transporting an alimentary bolus to be swallowed, from an oral cavity to a stomach).
Dysphagia is developed by degraded kinetic functions caused by advanced age, stroke such as brain infarct, cranial nerve degeneration disease (such as perkinsonism), and the like. In rapidly aging advanced countries, including Japan, dysphagia is found clinically frequently. Under dysphagia, an alimentary bolus may enter a bronchial tube (air passage), lung or the like, and pneumonia or the like, and it causes high temperature. Many cases have been recognized in which elderly persons having weakened body strength face a crisis of life.
Under these circumstances, a videofluoroscopic examination of swallowing (VF) is used most commonly as a method of correctly evaluating and grasping dysphagia. VF requires an X-ray radiographic apparatus in order to grasp a swallowing state, and a test subject swallows imaging agent such as barium sulfate to monitor a motion of alimentary bolus. A swallowing operation is constituted of a series of rapid motions, and these motions are likely to be missed if an X-ray radiographic apparatus only is used. Therefore, it is general that rapid motions are recorded in a video player for evaluations. However, VF is an examination having a possibility of aspiration, choke or the like, and careful attention is required. Furthermore, since an X-ray radiographic apparatus of a large size is required, there arise problems of radioactive exposure, time restrictions, cost and the like.
Another method used in recent years is a method of evaluating dysphagia with an endoscope using a fiber scope. This method is called a videoendoscopic examination of swallowing (VE). As compared to VF, VE has the advantages that the apparatus can be transported easily to a bed side or the like for examination, and evaluation is possible for the state of mucous membranes and tissues of a pharynx and larynx, for retained saliva and for others. However, a test subject feels uncomfortable when a fiber is inserted into a nasal cavity, and measurements are not simple because a fiber scope apparatus is required. From these reasons, VE is not still used widely. Further, at the climax of swallowing when an alimentary bolus enters the pharynx, a pharynx wall closes and a space in the pharynx is crushed. There arises therefore a problem that a view field of the endoscope becomes unclear, and observation cannot be made during the time period while the swallowing organ moves most frequently in a short time. This time period is called “whiteout” indicating a limit of VE examination.
As an approach to solving the problems associated with VF and VE, JP-A-2005-304890 (Patent Document 1) proposes a method of simply and accurately detecting dysphagia without burden on a patient. This approach by Patent Document 1 is characterized in that electrodes are attached to the surfaces of muscles associated with swallowing to record a surface electromyogram, that a microphone is used for recording swallowing sounds, that an acceleration sensor is used for recording vibrations while the larynx is raised, and that the acquired data is subjected to a neural network learning process to discriminate dysphagia.
According to Patent Document 1, however, it is necessary to form a database of the electromyogram, swallowing sounds and acceleration sensor data regarding the dysphagia, and to perform a neural network pattern learning. It takes, therefore, labor and time. Further, Patent Document 1 does not describe at all a discrimination method for healthy person so that operability is insufficient. Furthermore, without considering a relation between measured data, individual parameters are used for pattern learning to output only a discrimination result. It is therefore impossible to represent the degree of dysphagia by a visual representation. As above, Patent Document 1 does not describe at all how waveforms of measured data are compared, how the degree of dysphagia is directly judged from waveforms or the like, and means for simple judgment. Visual representation is therefore insufficient, and the degree of dysphagia and the like are difficult to be grasped crinically.
“Analysis of Beer Drinking Motion using Swallowing function evaluation system SFN-1” by Shohei FUJITA and five others, IEICE Technical Report MBE2006-7(2006-5), The Institute of Electronics, Information and Communication Engineers, May 2006, pp. 25-28 (Non-Patent Document 1) and JP-A-2006-95264 (Patent Document 2) propose a swallowing function evaluation system utilizing a pressure sensor (for detecting a larynx motion), a surface electromyogram and a vibration pickup (for detecting swallowing sounds). However, similar to Patent Document 1, Non-Patent Document 1 independently evaluates the parameters of each measured data (a cumulative value of an electromyogram, a time when an output of the pressure sensor becomes largest, an average period, a swallowing sound power), and does not describe at all how waveforms of measured data are compared, how the degree of dysphagia is directly judged from waveforms or the like, and means for simple judgment. Visual representation is therefore insufficient, and the degree of dysphagia and the like are difficult to be grasped crinically.
Non-Patent Document 1 proposes a measuring method by which four pressure sensors are disposed on a front surface of a thyroid cartilage at a pitch of 8 mm, and a sensor box fixing each pressure sensor is fixed to the neck by wounding a magic tape (registered trademark) around the neck. However, the four pressure sensors at spaced positions are insufficient for monitoring a continuous motion in an up/down direction of the thyroid cartilage. This arrangement provides only a precision sufficient for detecting a swallowing motion period, and it is also a demerit that the measuring method by wounding the magic tape (registered trademark) has strong obstructive nature and a test subject feels uncomfortable. The disclosure contents of Non-Patent Document 1 and Patent Document 2 do not disclose at all how waveforms of measured data are compared, how the degree of dysphagia is directly judged from waveforms or the like, and means for simple judgment. Visual representation is therefore insufficient, and the degree of dysphagia and the like are difficult to be grasped crinically.
Patent Document 1, Patent Document 2 and Non-Patent Document 1 disclose the methods basically using an electromyogram. However, since the methods using the electromyogram require a ground electrode and an earth electrode as described in Non-Patent Document 1, the number of electrodes increases, and handling the electrodes becomes complicated. Further, as described in Patent Document 1, since the larynx has four muscles (a geniohyoid muscle, a thyrohyoid muscle, a sternohyoid muscle, and a sternomastoid muscle), the method using an electromyogram has a demerit that the measurement results may differ unless the electrodes are disposed at correct positions of the larynx. This demerit exists always when an electromyogram is used. When a patient or novice nurse takes an electromyogram, the electrodes cannot be disposed correctly or handled properly. If disposable electrodes are used, there arises another problem of cost.
JP-A-9-248282 (Patent Document 3) discloses a method of detecting organism signals generated at a throat by mounting two acceleration sensors on an elastic stripe. This method aims at detecting voice signals, pulse signals and the like. Although this method detects mainly swallowing sounds, signals representative of a throat motion enter slightly. It is difficult to separate these signals and to use this method for dysphagia evaluation.